First of all, I must say this is an informative guide only. I do not recommend doing this.
Also you must have a Jailbroken Device.
2. Go to Sources, Edit, Add
3. Enter http://hackulo.us/
4. Search "AppSync"
5. Select and Install Correct Version matching Your iOS
- To find your iOS version, go to settings > general > about > look for version
For device only skip to step 12. For Device and computer continue to step 6.
6. On Your Computer Go to http://apptrackr.org/
7. Search For the App You Want
8. Scroll Down and Click a Download Link.
9. When download has finished, move file into your iTunes Library
- This location may vary for some but mine is Music > iTunes > iTunes Media > Mobile Apps
10. Double Click the Downloaded File to Add it to Your iTunes Library
11. Sync for Device
If you want to know how to do this without your computer keep reading
12. Back on Cydia Searc Intallous and Download That
13. Go to Your Home Screen and Open Installous
14. Search the App You Want and Touch Download
15. Touch a Download Link
16. When it is Finished It Should then Install
WARNING: The apps that you download on your device only will be erased when syncing your device.
To avoid this, either use steps 6 - 11 first or before syncing follow steps 6 - 11 to keep the apps from being erased.
Just remember I do not recommend doing this and this is only for information.